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The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

FIV May Not Be As Bad As We Think It Is

One title leapt off the page as I was looking over the listing of sessions available at the recent American Veterinary Medical Association Convention — Feline Immunodeficiency Virus: Does it Really Cause Disease?

I have long counseled owners that Feline Immunodeficiency Virus (FIV) is not an immediate death sentence, but short of the cat succumbing to an unrelated illness or injury, I’ve always thought that the disease would eventually be fatal. Has something changed in our understanding of FIV? Intrigued, I marked that session as a “must see.”

The talk was given by Dr. Sue VandeWoude, Professor and Associate Dean for Research in the College of Veterinary Medicine and Biomedical Sciences at Colorado State University. Her laboratory studies FIV “in the context of an animal model for HIV/AIDS and as an agent useful for investigation of Ecology of Infectious Disease in charismatic large felid species such as pumas and bobcats.”

I provided some basic FIV information in a post I wrote last year. What follows are some of the more interesting tidbits I picked up from Dr. VandeWoude, paraphrased from the convention notes she provided:

Between 1 and 25% of domestic cat populations are infected with one of 5 viral clades [variants of FIV].

FIV infection may be relatively asymptomatic in cats for many years, and some studies suggest it does not result in significant morbidity [illness] for infected animals. Nondomestic felid species, including puma (P. concolor) and lions (P. leo), are infected with distinct FIV strains that are not typically associated with overt disease.

FIV infects activated T cells [a type of cell important for immune function] and after acute symptoms (lymphadenopathy [swollen lymph nodes], fever, transient weight loss) typically enters a subclinical phase that lasts for months to years. Many cats live for years in the subacute phase with minimal noticeable disease, particularly when they live in indoor situations with limited exposure to other animals [although opportunistic infections and conditions such as gingivitis, lymphoma, and neurologic symptoms may arise].

FIV-positive animals in multi-cat households may transmit infection to uninfected cohorts, but the disease is not highly contagious.

After months to years of asymptomatic infection, for reasons that are not well understood, host immunologic control of FIV replication fails, resulting in increases in plasma viremia [virus in the blood stream], decreases in CD4 T cells, and increased susceptibility to infections and opportunistic diseases.

Highly virulent strains of FIV have been described, but are rare. These isolates can result in rapid immunological decline, high rate of cancer occurrence, and death within weeks to months following infection.

Dr. VandeWoude also talked about the FIV vaccine, mentioning that it not only provides immunity to the variants of FIV included in the vaccine but also offers “reasonable” cross-protection against the types that are not. However, many veterinarians have been reluctant to recommend the vaccine because it makes immunized individuals appear to have the disease on the most commonly used types of FIV tests.

Now that it looks like FIV infection is not the threat we once thought it was, use of this vaccine seems to make even less sense except in the most extreme of circumstances.

Comments 2

Dr Coates, I agree with you wholeheartedly about the waste of time and money involved in the vaccine. We had a salesperson trying to push it onto our veterinarian and when I asked him about the issues I had read about, I got the worst case of bafflegab you could imagine, although you probably had it too. In our case, we took in an aggressive FIV+ cat and would have loved to have been able to protect the other cats, but couldn't trust the information being spread by the company. For starters, the vaccine didn't cover the clade in known to be in our area, and when one added the fact that the efficacy was about 80% at its best, we decided that a permanent separation between him and our other residents was a much more prudent choice.

After talking to a lot of FIV+ cat owners, and reading everything there is about the clades, (or was back then), I have come to the conclusion that depending upon the clade you might find different vulnerabilities in the cats. Our boy would have been able to be with the others if he only had problems with his teeth, but other than the one he clearly lost while fighting other strays, his teeth were very strong, causing us a number of emergency visits ourselves. DH and I can both assure people that humans don't catch FIV from cats, in fact, in spite of all the stitches I earned, a HIV blood test I had a couple of months ago in a general health check came out negative, years later. Same for DH. Legolas's teeth were perfect, unfortunately for him. If he was vulnerable to stomatitis, he would have stood a chance of being assimilated with his friends.

Legolas did end up dying of a heart attack after refusing to eat when the dog he loved so much died. Up to that point, we think he underststood he had handed us a problem, and gave us plenty of laughter and good experiences in all the years we housed him.

I once asked a lab vet if there was a chance of gathering the type of information on clades that could be helpful, and while she was very interested in Legolas's lab results every year, she wasn't forthcoming with any possibilities on clade characteristics. For some reason there is a very strong reluctance to test for clades, and that part I never did manage to figure out while we were going through our own experience.

We did love him so much that I have never managed to put a final post on his blog describing his demise as it was so very very sad for us all. http://legolasourfivboy.blogspot.ca/

I have an FIV+ kitty and luckily he's a lover, not a fighter. Yes, he moved into my back yard and eventually my home, so there's no telling where he got it.

When I took him to be neutered, the vet called to tell me had had tested positive for FIV and sounded so relieved when I basically said, "So?"

I do not fear the other kitties will contract FIV and have never regretted taking him into my family 7 years ago. We keep a close eye on him (he has a little stomatisis on one tonsil) to be sure he's in good health and he gets a full checkup at least once every 4 months.